Handheld Lidar Creates Leaning Tower of Pisa in 3-D

Photonics.comSep 2013
HIGHETT, Australia, Sept. 27, 2013 — Using a handheld laser mapping system, Australian researchers have created the first-ever 3-D map of the inside of Italy’s Leaning Tower of Pisa, a site whose cramped stairs and complex architecture have prevented previous mapping technologies from capturing its interior.

Developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, the technology — Zebedee — incorporates a laser scanner that sways on a spring to capture millions of detailed measurements of a site as the user walks through.

Display of final Zebedee 3-D map of the Leaning Tower of Pisa. Images courtesy of Commonwealth Scientific and Industrial Research Organisation.
“This technology is ideal for cultural heritage mapping, which is usually very time consuming and labor intensive,” said Dr. Jonathan Roberts, research program leader at CSIRO’s Computational Informatics Division. “It can often take a whole research team a number of days or weeks to map a site with the accuracy and detail of what we can produce in a few hours.”

The device uses lidar (light detection and ranging) technology, in which an IR laser measures ranges to surfaces in the environment. Zebedee’s laser scanner is mounted on a spring, making it lightweight and ensuring a wide-scanning field of view. The spring converts the natural motions of the operator into a suitable sweeping motion of the scanner, and an inertial sensor provides rough measurements of the spring’s rotations.

Dr. Jonathan Roberts, program leader for CSIRO’s Computational Informatics Division, holds the 3-D scanner in front of the Leaning Tower of Pisa.
Specialized software then converts the system’s laser data into a detailed 3-D map of the environment and an accurate record of the trajectory followed. The 3-D maps are represented as point clouds, which consist of millions of points expressed in a common coordinate frame.

During “Project Pisa,” CSIRO collaborated with Italian scientists from Scuola Superiore Sant’Anna (SSSA), who believe the research will have significant impact on preserving the cultural heritage of the site.

“Our detailed record of the Leaning Tower of Pisa may one day be critical in being able to reconstruct the site if it was to suffer catastrophic damage due to natural disasters such as a fire or an earthquake,” said Franco Tecchia, assistant professor at the Perceptual Robotics Laboratory. “Having a detailed 3-D model of the world’s most significant cultural heritage sites could also be used to allow people who cannot physically visit these sites to better understand and appreciate their history and architecture.”

A screenshot of a 3-D point cloud created from CSIRO’s Zebedee scan of the Leaning Tower of Pisa.
CSIRO worked with 3-D Laser Mapping, a developer of laser scanning solutions, to commercialize the Zebedee research into the ZEB1 product. The Zebedee research was awarded a 2013 Eureka Prize for Innovative Use of Technology. The system was also named the winner of the Research and Development category at the iAwards, Australia’s information and communications technology awards program.

An acronym of light detection and ranging, describing systems that use a light beam in place of conventional microwave beams for atmospheric monitoring, tracking and detection functions. Ladar, an acronym of laser detection and ranging, uses laser light for detection of speed, altitude, direction and range; it is often called laser radar.